Release kinetics of cinnamaldehyde, eugenol, and thymol from sustainable and biodegradable active packaging films

Active packaging films can be formulated with biodegradable polymer loaded with natural antimicrobial compounds (NAC) as biodegradable alternatives to traditional plastic packaging for food. Essential oil compounds, naturally found in the plants, have antimicrobial activity against microorganisms. In this work, they are encapsulated in liquid lipid nanoparticles (LLN) or solid lipid nanoparticles (SLN) to control and enhance their solubility and stability and control kinetic release. In this study, the release kinetics of thymol, cinnamaldehyde, and eugenol, from pullulan-based films were studied as a function of lipid structure (liquid vs solid) and carrier particle concertation. The crystallization temperature of SLN (10.2 °C) decreased with incorporation of NAC (6.8 °C in SLN loaded with 1 % cinnamaldehyde). Increasing NAC significantly decreased (p < 0.05) the crystallization temperature of SLN. The SLN structure was similar in films to emulsions as their melting and crystallization temperatures were similar (p > 0.05). The NAC release rate from SLN films was twice than that from LLN films due to higher aqueous partitioning. The release rate in SLN films increased 100 %, 50 %, and 5 % for thymol, eugenol, cinnamaldehyde, respectively, when NAC concertation in the particles increased from 1 % to 2 %. Thymol had highest release rate (0.93 ppm/min) from SLN loaded with 2 % NAC films than that of eugenol and cinnamaldehyde (0.40 and 0.15 ppm/min, respectively). This study shows that the NAC-loaded pullulan films can be used as active antimicrobial packaging film for food applications with controlled release of active compounds.